JP2009256484A - Method for producing hard polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing hard polyurethane foam having low density, excellent workability, curing properties, dimensional stability, and flame retardancy without using a heavy metal catalyst. <P>SOLUTION: In the method for producing hard polyurethane foam, the hard polyurethane foam is produced by using carbon dioxide generated by reaction between water and a polyisocyanate component and carbon oxide in at least one state among a supercritical state, sub-critical state, and a liquid state together as a foaming agent, and adding water and carbon dioxide in the liquid state to a polyol component before mixing the polyisocyanate component and the polyol component together. In the polyol component, three kinds of substances, which are (i) tris(dimethylaminopropyl)hexahydro-s-triazine, (ii) triethylenediamine, and (iii) an alkali metal salt of carboxylic acid, are contained as catalysts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid polyurethane foam having low density and excellent workability, dimensional stability, and flame retardancy.

Rigid polyurethane foam is excellent in heat insulation, moldability and the like, and is widely used as a heat insulating material and a structural material for houses, refrigerated warehouses and the like.
At present, in the production of this rigid polyurethane foam, a method of utilizing carbon dioxide generated by the reaction of water and polyisocyanate as a foaming agent is common.

  However, when a rigid polyurethane foam is produced using only such carbon dioxide, the rate at which carbon dioxide in the bubbles (cells) formed in the foam diffuses out of the bubbles is the speed of the air flowing into the bubbles. Since it is faster than the speed, there is a drawback that the internal pressure of the bubble is lowered and the bubble is easily contracted.

In order to solve this problem, the present inventor previously used carbon dioxide in a supercritical state, subcritical state, or liquid state as a blowing agent in addition to carbon dioxide generated by the reaction of conventional water and polyisocyanate. A technique of improving the dimensional stability by bringing the cell shape closer to a sphere by using the combination is proposed (see Patent Document 1).
In order to obtain good workability, heavy metal catalysts such as lead have been used as a catalyst (see Patent Document 1). However, the use of this catalyst may be limited due to its influence on the environment and human body. It is being desired.

On the other hand, when spraying onto a construction object such as concrete or plywood in a spray method (a method in which a polyisocyanate component and a polyol component are mixed with a foaming machine and sprayed onto the construction object to obtain a rigid polyurethane foam), the construction object There was a problem of protruding in the lateral direction of the object (so-called “horizontal spread”). And when there was a horizontal spread, the thickness of the formed heat insulation layer became non-uniform | heterogenous, and cutting finishing was required.
In addition, in this spray method, there is an operation of confirming whether or not a predetermined thickness is applied after spraying, but there is a problem that it is difficult to measure the thickness if the foam surface is sticky.
JP 2004-107376 A

  In consideration of the above points, the present invention provides a method for producing a rigid polyurethane foam having a low density, excellent workability, dimensional stability, and flame retardancy without using a heavy metal catalyst such as lead. Is an issue.

As a result of studies to solve the above problems, the present inventors have
In the production of rigid polyurethane foam, by combining three specific types of catalysts, both urethanization and trimerization (isocyanuration) are promoted sufficiently and well-balanced without using a heavy metal catalyst. It has been found that a rigid polyurethane foam having excellent workability, dimensional stability and flame retardancy can be obtained.

The present invention has been achieved under such knowledge, and the gist thereof is as follows.
(1) As a blowing agent, by using together carbon dioxide generated by the reaction of water and a polyisocyanate component and carbon dioxide in at least one of a supercritical state, a subcritical state, and a liquid state, and polyisocyanate A method for producing a rigid polyurethane foam by adding water and carbon dioxide in a liquid state to the polyol component before mixing the component and the polyol component,
In the polyol component, at least three kinds of (i) tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) triethylenediamine, and (iii) alkali metal salt of carboxylic acid are contained as a catalyst. A method for producing a rigid polyurethane foam, characterized in that:
(2) 2 to 5 parts by weight of tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) 2 to 7 parts by weight of triethylenediamine, based on 100 parts by weight of polyol in the polyol component, (iii) 2) The alkali metal salt of carboxylic acid is contained in an amount of 2 to 5 parts by weight. The method for producing a rigid polyurethane foam as described in (1) above.

According to the production method of the present invention, since no heavy metal catalyst such as lead is used, there is no influence on the environment and the human body, and since it has excellent workability, dimensional stability, and flame retardancy, it is used for building materials, etc. A rigid polyurethane foam suitable for the above can be obtained.
And, since the hard polyurethane foam by the production method of the present invention has very good workability, it is particularly difficult to cause lateral spread when sprayed onto a construction object in the spray method, and has excellent smoothness. In addition, a foam having excellent curability can be obtained, and the industrial utility value is extremely large.
In addition, the manufacturing method of this invention is applicable also to the method of producing a foam continuously besides the spray method.

  Moreover, the rigid polyurethane foam by the manufacturing method of this invention is easy to pass the flame-retardant material by an exothermic test.

In the production method of the present invention, in order to improve the mixing of the polyisocyanate component and the polyol component and to make the foamed cells uniform and fine, carbon dioxide generated by the reaction of water and the polyisocyanate component is used as a foaming agent. And carbon dioxide in at least one of a supercritical state, a subcritical state, and a liquid state are indispensable requirements. This water and carbon dioxide in a liquid state include a polyisocyanate component and a polyol component. Before mixing, it is added to the polyol component.
Based on such production conditions, in the present invention, at least (i) tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) triethylenediamine, and (iii) carboxylic acid is used as a catalyst in the polyol component. It is important that three kinds of alkali metal salts are contained.

  About the apparatus used with the manufacturing method of this invention, the catalyst which consists of at least 3 types of said (i)-(iii) is previously contained in a polyol component, and the water and the carbon dioxide of a liquid state to a polyol component are included. It is necessary to set the addition time before mixing the polyisocyanate component and the polyol component. For example, an apparatus as shown in FIG. 1 can be used.

In FIG. 1, the polyisocyanate component 1 is measured by a metering pump 3 connected from a tank 2 via a pipe 4, passes through a heater unit 18 for heating to a set temperature, and a heating hose 19, and then mixed in a mixing head 5. It is transferred to. On the other hand, the polyol component 11 is measured by a metering pump 14 connected from a tank 12 via a pipe 13 and transferred to a mixing head 5 through a heater unit 10 and a heating hose 9 for heating to a set temperature. The
Water in the water storage tank 15 is metered by a metering pump 16 that operates in conjunction with each pump, is introduced into the polyol component through a pipe 17 connected to the pipe 13, and is being transferred through a flow path to the mixing head 5. Mixed into the polyol component.
Carbon dioxide in the carbon dioxide cylinder 6 is measured by a metering pump 7 that operates in conjunction with each pump, is introduced into the polyol component through a pipe 8 connected to the pipe 13, and is being transferred through a flow path to the mixing head 5. In the polyol component.
At this time, the mixing efficiency may be further increased by providing a static mixer between the input position of carbon dioxide and water and the mixing head.
In the mixing head 5, the polyisocyanate component and the polyol component (mixed with carbon dioxide and water) are impinged and mixed and ejected into the atmosphere with a liquid or foam mist. It is formed.

In such a production method, in the present invention, at least (i) tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) triethylenediamine, and (iii) carboxylic acid are used as the catalyst added to the polyol component. Three types of alkali metal salts are used.
The total addition amount of the three kinds of catalysts is preferably 6 to 17 parts by weight with respect to 100 parts by weight of the polyol component.
If the total amount of these three kinds of catalysts is too small, both the urethanization and the isocyanurate reaction are not sufficiently promoted, and it is difficult to obtain desired workability, curability and flame retardancy. On the other hand, if the amount is too large, the cell shape has an anisotropy extending in the foaming direction, so that the strength in the direction perpendicular to the foaming direction is weakened, and the dimensional stability tends to be very poor because of shrinkage deformation.

In the present invention, (i) 2 to 5 parts by weight of tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) 2 to 7 parts by weight of triethylenediamine, based on 100 parts by weight of polyol in the polyol component, iii) It is preferable that 2-5 weight part of alkali metal salts of carboxylic acid are contained.
(I) Tris (dimethylaminopropyl) hexahydro-s-triazine is highly effective in enhancing the curability of the urethane foam (prevents stickiness of the foam surface after foaming), and if less than 2 parts by weight, the curability is inferior. If it exceeds the portion, anisotropy occurs in the cell shape and shrinkage deformation occurs, so that the dimensional stability is deteriorated.
(Ii) Triethylenediamine contributes to shortening the rise time by accelerating the urethanization reaction, and if it is less than 2 parts by weight, the workability and smoothness are inferior, such as lateral spread, and if it exceeds 7 parts by weight Anisotropy occurs in the cell shape and shrinkage deformation causes dimensional stability to deteriorate.
(Iii) As the alkali metal salt of carboxylic acid, one or two or more kinds of potassium octylate and potassium acetate can be used, and the effect of promoting the isocyanuration reaction and improving the flame retardancy is large, and 2 weight When the amount is less than 5 parts by weight, the flame retardancy is inferior. When the amount exceeds 5 parts by weight, anisotropy occurs in the cell shape and shrinkage deformation occurs, resulting in poor dimensional stability.

In the present invention, as the catalyst, only the above three kinds of compounds may be used, or other catalysts may be used in combination depending on the application.
Examples of other catalysts that can be used in combination include trimethylaminoethylethanolamine, tetramethylalkylenediamine, dimethylethanolamine, dimethylcyclohexylamine, 1,2-dimethylimidazole, pentamethyldiethylenetriamine, and bis (2-dimethylaminoethyl) ether. Examples of these catalysts include amine catalysts, and these catalysts may be used alone or in combination of a plurality of catalysts.

As the foaming agent, carbon dioxide generated in a reaction between water and a polyisocyanate component is used in combination with carbon dioxide in a supercritical state, a subcritical state, or a liquid state.
Disadvantages of using only carbon dioxide generated by the reaction of water and polyisocyanate by using carbon dioxide in the supercritical state, subcritical state, or liquid state in combination:
α) In order to prevent shrinkage, it is necessary to increase the density, which increases the cost.
β) On the contrary, a large amount of water is required to reduce the density, excessive urea bonds occur, and the resulting urethane foam tends to be brittle.
Etc. are eliminated, resulting in better workability and dimensional stability.

  In the present invention, the amount of carbon dioxide added in the polyol component together with water depends on the density of the rigid polyurethane foam to be produced, the polyisocyanate component, and the viscosity of the polyol component. It is preferable that it is 0.5 to 3 weight% with respect to the sum total of a polyol component, More preferably, it is 1 to 2 weight%.

The amount of water added to the polyol component is preferably 4 to 8 parts by weight with respect to 100 parts by weight of the polyol in the polyol component.
If it is less than 4 parts by weight, foaming is insufficient and the density of the hard polyurethane foam to be produced becomes high, and it becomes difficult to pass the flame retardant material by the exothermic test. On the other hand, when the amount exceeds 8 parts by weight, excessive urea bonds are formed, and the resulting rigid polyurethane foam tends to be brittle and the adhesiveness tends to decrease.

In the present invention, water and liquid carbon dioxide are added to the polyol component, and the polyol component is heated to 45 to 50 ° C. and 6 MPa or more (preferably 7 to 7.5 MPa) before mixing with the polyisocyanate component. By heating and pressurizing, carbon dioxide in a liquid state can be brought into a supercritical state and a subcritical state.
In the case of using the apparatus configured as shown in FIG. 1, the polyisocyanate component and the polyol component in which liquid carbon dioxide and water are mixed in the flow path to the mixing head 5 as described above. The carbon dioxide in the above state can be appropriately prepared by appropriately setting the temperature and pressure within the above range.

  Carbon dioxide has a high diffusion coefficient in the supercritical state or the subcritical state, and exhibits a remarkable effect of making the bubbles of the rigid polyurethane foam fine. The action of the three kinds of catalysts of the present invention is added to this, and the workability can be improved by accelerating the reaction rate between the polyol component and the polyisocyanate component without using a heavy metal catalyst.

  In the present invention, “subcritical carbon dioxide” means carbon dioxide in a liquid state in which the pressure is not less than the critical pressure of carbon dioxide and the temperature is lower than the critical temperature, or the critical pressure of carbon dioxide. And carbon dioxide in a liquid state whose temperature is equal to or higher than the critical temperature, or both temperature and pressure are lower than the critical point. Further, “supercritical carbon dioxide” refers to carbon dioxide whose pressure is equal to or higher than the critical pressure of carbon dioxide and whose temperature is equal to or higher than the critical temperature.

The polyol component used in the present invention may be an aromatic polyester polyol alone or a combination of an aromatic polyester polyol and a polyether polyol.
Examples of aromatic polyester polyols include polyols derived from phthalic anhydride, polyethylene terephthalate scrap, dimethyl terephthalate process residues, and the like.
As the polyether polyol, for example, an amino polyol obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to ethylenediamine, tolylenediamine, triethanolamine, a Mannich condensation product, or the like is preferable.

When an aromatic polyester polyol and a polyether polyol are used in combination, 60 to 90 parts by weight of the aromatic polyester polyol and 40 to 10 parts by weight of the polyether polyol are contained with respect to 100 parts by weight of the total polyol component. It is preferable to do.
If the content of the aromatic polyester polyol is less than 60 parts by weight, the flame retardant material in the exothermic test may fail, and if it exceeds 90 parts by weight, the tendency of the foam to be hardened is increased.
The particularly preferred content of the aromatic polyester polyol is 70 to 80 parts by weight.

Examples of the polyisocyanate component used in the present invention include polymethylene polyphenyl isocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,6-dimethyl-1, Examples include 3-phenylene diisocyanate, 4,4′-dibenzyl diisocyanate, 9,10-anthracene diisocyanate, 4,3′-dimethyl-4,4′-diphenyl diisocyanate, and xylylene diphenylmethane diisocyanate. Or two or more of them may be used in combination.
The amount used is suitably NCO / OH equivalent ratio of 1.0 to 2.0.

  In the method for producing a rigid polyurethane foam of the present invention, for example, a polyoxyalkylene-based foam stabilizer such as polyoxyalkylene alkyl ether, a silicone-based foam stabilizer such as organosiloxane, a compatibilizer such as oxyethylene alkylphenol, Additives commonly used in the production of rigid polyurethane foams such as flame retardants, thickeners, colorants, stabilizers, etc. may be used.

Examples of the flame retardant include phosphoric esters such as trimethyl phosphate, triethyl phosphate, trischloropropyl phosphate, and the addition amount is preferably 20 to 40 parts by weight with respect to 100 parts by weight of the polyol.
If it is less than 20 parts by weight, the flame retardant material by the exothermic test may be rejected. Phosphoric acid esters and the like have the effect of improving brittleness, which is a drawback of rigid polyurethane foams that use water as a foaming agent in order to impart plasticity to the urethane resin, and improving adhesion. The strength tends to decrease due to the conversion.

The rigid polyurethane foam obtained by the above production method preferably has a closed cell ratio of about 70 to 80% and a moisture permeability coefficient of 360 ng / (m ² · S.Pa) or less at a thickness of 25 mm.
Moreover, it is preferable that the density of the rigid polyurethane foam obtained by the manufacturing method of this invention is 20-40 kg / m < ³ >. Such a low density is economical as a product.

Examples 1-7, Comparative Examples 1-6
(Raw materials used)
・ Polyisocyanate: Polymethylene polyphenyl isocyanate (NCO content 30%)
Polyol A: Polyethylene terephthalate polyester polyol (hydroxyl value 110)
Polyol B: Mannich polyether polyol (hydroxyl value 315)
・ Foam stabilizer: Silicone foam stabilizer (trade name “L-5420” manufactured by Toray Dow Corning Co., Ltd.)
Catalyst (i): Tris (dimethylaminopropyl) hexahydro-s-triazine (trade name “Polycat 41” manufactured by Air Products Co., Ltd.)
Catalyst (ii): Triethylenediamine (trade name “TEDA-L33” manufactured by Tosoh Corporation)
Catalyst (iii): Potassium octylate (trade name “P-9540” manufactured by Perlon Co., Ltd.)
Flame retardant: Trischloropropyl phosphate (trade name “TMCPP” manufactured by Daihachi Chemical Co., Ltd.)
・ Thickener: Propylene carbonate (trade name “PC1000” manufactured by Asahi Glass Co., Ltd.)

In accordance with the formulation shown in Table 1, a polyol component and a polyisocyanate component are mixed using a Graco model FF1600 foaming machine as the apparatus shown in FIG. 1, and spray foamed onto a 12 mm thick plywood and a calcium carbonate board. To obtain a rigid polyurethane foam.
At this time, the temperature and pressure in the heating hoses 9 and 19 of the polyol component and the isocyanate component were 50 ° C. and 7 MPa, respectively.

About each obtained foam, workability ("horizontal spread" and "curability"), density (kg / m < ³ >), closed cell rate (%), moisture permeability coefficient ng / (m < ² > .S.Pa), Dimensional stability and flame retardancy were measured, and the results are shown in Table 1.

Workability ("horizontal spread" and "curability") was observed during spray foaming.
・ As for workability (horizontal spread), when sprayed onto a plywood board, if there is no protrusion of the foam on all sides of the plywood board, there will be no horizontal spread, and if the foam protrusion is less than 20 mm, “△”, the foam will protrude. The case of 20 mm or more was designated as “x”.
-As for workability (curability), 10 seconds after spraying on a plywood board, “O” indicates that the foam surface is not sticky, and “X” indicates that the foam surface is sticky.

The density, closed cell ratio, moisture permeability coefficient, dimensional stability, and flame retardancy were measured for a rigid polyurethane foam spray foamed to a thickness of 30 mm according to the following method.
The density (kg / m ³ ) was measured by weighing a test piece of 70 mm × 70 mm × 20 mm.
-The closed cell ratio (%) was measured based on ASTM D2856.
The moisture permeability coefficient (ng / (m ² .S.Pa)) was measured based on JIS Z0208.

-As for dimensional stability at high temperature, after leaving a test piece of 70 mm × 70 mm × 20 mm at 100 ° C. for 48 hours, the presence or absence of deformation was examined.
-As for dimensional stability at low temperature, after leaving a test piece of 70 mm × 70 mm × 20 mm at −20 ° C. for 48 hours, the presence or absence of deformation was examined.
-For flame retardancy, a heat release test was conducted on a test piece cut to a foam thickness of 20 mm after spray foaming to a thickness of 30 mm on a 12 mm thick calcium plate, and a pass / fail judgment was made.

It is a figure which shows the one aspect | mode of the manufacturing apparatus of a rigid polyurethane foam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyisocyanate component 2 Polyisocyanate component tank 3 Pump 4 Piping 5 Mixing head 6 Liquid carbon dioxide cylinder 7 Metering pump 8 Piping 9 Heating hose 10 Heater 11 Polyol component 12 Polyol component tank 13 Piping 14 Metering pump 15 Water storage tank 16 Metering pump 17 Piping 18 Heater 19 Heating hose

Claims (2)

By using, as a blowing agent, carbon dioxide generated by the reaction of water and a polyisocyanate component and carbon dioxide in at least one of a supercritical state, a subcritical state, and a liquid state, and a polyisocyanate component and a polyol A method of producing a rigid polyurethane foam by adding the water and liquid carbon dioxide to the polyol component before mixing the components,
In the polyol component, at least three kinds of (i) tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) triethylenediamine, and (iii) alkali metal salt of carboxylic acid are contained as a catalyst. A method for producing a rigid polyurethane foam, characterized in that: (I) 2 to 5 parts by weight of tris (dimethylaminopropyl) hexahydro-s-triazine, (ii) 2 to 7 parts by weight of triethylenediamine, and (iii) carboxylic acid with respect to 100 parts by weight of polyol in the polyol component 2. The method for producing a rigid polyurethane foam according to claim 1, wherein 2 to 5 parts by weight of an alkali metal salt is contained.

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